Internal combustion engines generate waste heat which can be captured by heat storage devices for use by other systems at subsequent periods. For instance, reservoirs storing fluid heated by engine coolant have been employed in some internal combustion engines. The energy in the heated fluid can be transferred to different engine systems. However, these heat reservoirs can be costly, bulky, and susceptible to damage. Moreover, previous operating methods for systems with heat storage reservoirs can interfere with other engine systems, such as cabin heating systems, necessitating tradeoffs in the control strategies of the different systems.
In one approach, to overcome at least some of the aforementioned drawbacks, a method for operating an engine system is provided. The method includes during a first operating condition, flowing oil from an oil sump to a heat exchanger attached to a reductant tank and transferring heat from oil flowing through the heat exchanger to reductant stored in the reductant tank. The method further includes during a second operating condition, flowing oil from the oil sump to the heat exchanger and transferring heat from the reductant stored in the reductant tank to oil flowing through the heat exchanger. The method enables heat energy to be transferred back and forth between the engine lubrication system and the reductant injection system to capture, store, and then later utilize the heat energy to improve engine warming during cold starts. The heat management method therefore enables engine cold start lubrication to be improved to reduce engine component wear and fuel consumption. Moreover, transferring heat energy to the reductant tank also enables operational improvements in the reductant injection system, allowing reductant to be injected at desired temperatures during engine operation and reduces the likelihood of the reductant solidifying in the reductant tank while the engine is not in operation.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.